Excess adipose tissue is the defining characteristic of obesity. The phenotype and function of adipose tissue are closely associated with many metabolic diseases, including type 2 diabetes mellitus, non-alcoholic fatty liver disease and dyslipidemia. Understanding adipose tissue function and biogenesis are critical to gain insights into the development of obesity and its co-morbidities. The New York Obesity Nutrition Research Center (NYONRC) includes about 50 federally-funded investigators. The Adipose Tissue Core (AT Core) provides an efficient and cost-effective means for investigators in our research base to study the characteristics and functions of adipose tissue in normal biology and pathologic states. Rationale for Adipose Tissue Core: The NYONRC has a large cadre of NIH-funded investigators who vary widely in their expertise and areas of investigation. To many of these investigators, characterizing the phenotype and function of adipose tissue is critical for their studies. The AT Core brings together the expertise and equipment to provide comprehensive adipose tissue analysis, which would otherwise be unavailable or significantly more expensive for individual NYONRC investigators. One example is that in the AT Core the sizing of adipocytes through histologic analysis of many sections of adipose tissue employs a Nikon light microscope with an automated stage system, CD camera and software that identifies and measures the size of each individual adipocyte in a field. Another example is that FACS analyses that the AT Core performs for NYONRC investigators requires development and validation of protocols for each combination of fluorescently tagged antibodies and the maintenance of two expensive FACS machines. The equipment required for these services was purchased by Columbia University. Because the NYONRC leverages the investments in equipment made by Columbia University, the AT Core is able to provide services that would otherwise be unavailable to NYONRC investigators or significantly more expensive.